1. Field of the Invention
Example embodiments relate to a method for manufacturing a semiconductor device. More particularly, example embodiments relate to a method for forming patterns in a semiconductor device.
2. Description of the Related Art
A semiconductor device generally includes elements having patterns of various structures formed on a semiconductor substrate. These elements may be electrically connected to perform various operations. Arranging elements in a unit area of a semiconductor device with a high degree of integration is actively being researched. For example, in semiconductor devices, the same pattern may be repeatedly arranged in a cell array of a semiconductor memory device including highly integrated memory cells and thus, a double exposure technology for forming these patterns is under development. However, in conventional double exposure technologies, a technical limitation is generally reached when a linewidth of a pattern is 40 nm or less.
FIGS. 1 through 4 illustrate a method for forming patterns using conventional double exposure technology.
Referring to FIG. 1, a material layer 12 used for forming patterns may be formed on a semiconductor substrate 10. A first mask layer 14 and a second mask layer 16 may be formed on the material layer 12. A first photoresist pattern 18 may be formed on the second mask layer 16.
Referring to FIG. 2, the second mask layer 16 may be patterned using the first photoresist pattern 18 as an etch mask to form a hard mask pattern 16p on the first mask layer 14. Next, the first photoresist pattern 18 may be removed, and a second photoresist pattern 20 may be formed on the first mask layer 14.
Referring to FIG. 3, the first mask layer 14 may be patterned using the second photoresist pattern 20 and the hard mask pattern 16p as etch masks to form a mask layer including a first pattern 14a and a second pattern 14b. The hard mask pattern 16p may be used to form the first pattern 14a and the second photoresist pattern 20 may be used to form the second pattern 14b. 
Referring to FIG. 4, the material layer 12 may be patterned using the first pattern 14a and the second pattern 14b as etch masks to form a first material layer pattern 12a and a second material layer pattern 12b. 
According to this conventional method, the first material layer patterns 12a and the second material layer patterns 12b may be alternately arranged on the substrate 10. However, in this conventional method, a pattern of a scale of 80 nm may be formed using light having a wavelength of 248 nm by dividing patterns having a small pitch into two groups and performing a double exposure.
However, in the conventional method using double exposure, if a mask layer for a first exposure process and a mask layer for a second exposure process are misaligned, the first material layer pattern 12a and the second material layer pattern 12b are misaligned. Accordingly, a difference between left and right intervals L1 and L2 of the second material layer pattern 12b may occur as illustrated in FIG. 5. Such a difference may cause defects in patterns. A pattern defect may occur when the first material layer pattern 12a and the second material layer pattern 12b contact each other. For example, the pattern defect X illustrated in FIG. 6 may occur if a resist used for forming the second photoresist pattern 20 remains in the vicinity of the hard mask pattern 16 and/or if the first mask layer 14 remains between the second photoresist pattern 20 and the hard mask pattern 16. Further, the pattern defect X may occur if a pitch of the pattern is small or if the mask layer for the first exposure process and the mask layer for the second exposure process are misaligned.